Time series data modeling is generally performed using the assumption of homoscedasticity or residual variance that is constant over time. However, the homoscedasticity assumption cannot answer the problem of volatility in economic and business time series data, because generally data on economics and business have residual variances that always change over time. Therefore, a model developed with the assumption of not constant variance is known as heteroskedasticity model. Multivariate GARCH model is a development of the univariate GARCH model. The multivariate GARCH model can be viewed as a conditional heteroskedasticity model in a multivariate time series. This paper discusses the parameterization of covariance matrices such as Vech model representation, BEEK model and Constant Correlation model. For parameter estimation the maximum likelihood method is used. Furthermore, multivariate GARCH model application is applied for multivariate model. In this research, the data used are data on the prices of fresh fish in Manado. The fish price data is the price of Tuna, Skipjack (Cakalang), Cobe (Tongkol), Kite (Malalugis) and Selar fish (Tude). The ARCH effect test results show that the data meet the assumption of non-constant variance (heteroscedasticity). GARCH mutivariate modeling in the form of a VEC diagonal model gives the results of the price volatility of fresh fish in Manado